(function(){
	let root = (typeof self == "object" && self.self == self && self) || 
	(typeof global == "object" && global.global == global && global) ||
	this||
	{};
	let _ =function(){
	};
	root._ = _;
	_.reverse = function(str){
		return str.split("").reverse().join("");
	}
	_.each = function(data,fuc){
		if(typeof data == "arry"){
			for (var i = 0; i < data.length; i++) {
				fuc(data[]);
			}
		}
	}
})()

var p = new Promise(function(res,rej){
	setTimeOut(function(){
		res()
	},2000)
})

p2 = p.then(function(){
	return new Promise(function(res,rej){
		res("23")
	})
})

p3 = p2.then(function(){
	return new Promise(function(res,rej){
		setTimeout(function(){
			res("4")
		},2000)
	})
})